A quarter marathon is roughly a quarter of a full marathon, so it’s about 10.5 km (6.55 miles) in its most literal form, though many events round it to about 10 km (6.2 miles).

  • A full marathon is 42.195 km (26.2 miles), so one quarter is 10.54875 km (6.55475 miles), usually listed as 10.55 km or 6.55 miles.
  • Some races brand their quarter marathon specifically as 6.55 miles.
  • Other organizers and runners use “quarter marathon” more loosely to mean a 10K (10 km / 6.2 miles), since that’s close to one quarter of a marathon and is a very common race distance.

So if you see “quarter marathon” on a race signup, check the event details: it will almost always be between 10 km and 10.55 km (about 6.2–6.55 miles).